As is well known, the rotor of a vehicle AC generator is coupled with the output axle of an internal combustion engine through a coupling member such as a belt; transfer of torque between the internal combustion engine and the vehicle AC generator is implemented through a coupling member. Accordingly, the operation state of the vehicle AC generator provides a considerable effect to the operation status of the internal combustion engine. To date, with regard to a control apparatus for this kind of vehicle AC generator, there has been proposed technologies in which a vehicle AC generator and an internal combustion engine are integrally controlled (for example, refer to Patent Document 1).
FIG. 3 is a configuration diagram of such a conventional vehicle AC generator control apparatus as disclosed in Patent Document 1. In FIG. 3, a generator control apparatus 2 provided integrally with a vehicle AC generator 1 is provided with an external command reception unit 8 that receives an external command from an external unit 7 formed of an ECU (Engine Control Unit), an external command/voltage conversion unit 9 that converts a received external command value into a control voltage value, and an external command effective/ineffective determination unit 11 that determines whether the received external command is effective or ineffective.
The generator control apparatus 2 is further provided with a second target voltage command unit 10 that is capable of commanding an output voltage of the vehicle AC generator 1 in addition to the external command, a selector 12 that performs switching between the output of the external and/control voltage conversion unit 9 and the output of the second target voltage command unit 10 and then provides the selected output to a voltage control unit 6, a PWM control unit 5 that controls the on/off period of a switching device 15 formed of a power transistor so as to PWM-control the magnetic-field current of the vehicle AC generator 1, a voltage detection unit 4 that detects the output voltage of the vehicle AC generator 1, and the voltage control unit 6 that provides a PWM control value to the PWM control unit 5, based on the detected output voltage of the vehicle AC generator 1 and the output from the selector 12.
A rectifier 14 converts AC output power induced across an armature winding 13 into DC power and then supplies the DC power to a magnetic-field winding 3 and a high-capacitance capacitor 20. The output voltage of the capacitor 20 is supplied to a vehicle battery 22 and an electric load 23 by way of a DC/DC converter 21.
The external unit 7, which is an ECU, detects the operation status of an internal combustion engine (unillustrated), the state of a mechanical load, the state of the electric load 23, and the like, calculates a reference voltage value of the vehicle AC generator 1, based on the these detection results, and then transmits the external command corresponding to the calculated reference voltage value to the external command reception unit 8 of the generator control apparatus 2. In the case where the external command effective/ineffective determination unit 11 determines that the external command is effective, the voltage control unit 6 makes the PWM control unit 5 on/off-control the switching device 15 so as to PWM-control the magnetic-field current, based on the output voltage of the vehicle AC generator 1, detected by the voltage detection unit 4, and the control voltage value, from the external command/control voltage conversion unit 9, that is provided by way of the selector 12, so that the output voltage of the vehicle AC generator 1 is made to coincide with a value indicated by the external command.
In contrast, in the case where the external command effective/ineffective determination unit 11 determines that the external command is ineffective, the voltage control unit 6 makes the PWM control unit 5 on/off-control the switching device 15 so as to PWM-control the magnetic-field current, based on the output voltage of the vehicle AC generator 1, detected by the voltage detection unit 4, and the output, of the second target voltage command unit 10, that is provided by way of the selector 12, so that the output voltage of the vehicle AC generator 1 is made to coincide with the output of the second target voltage command unit 10.
The conventional vehicle AC generator control apparatus configured as described above controls the output voltage of the vehicle AC generator 1 in accordance with the external command that is given from the external unit 7 to the generator control apparatus 2 so that the internal combustion engine and the vehicle AC generator 1 are integrally controlled; thus, he conventional vehicle AC generator control apparatus can contribute to stabilization of control of an internal combustion engine and to improvement of gasoline mileage.